This invention concerns mechanical packaging techniques for arrays of computer disk drives in which the drives must be adequately cooled and at the same time provided with sufficient electromagnetic radiation shielding to meet prevailing emission standards.
Large computer storage systems use multiple magnetic, optical, or magneto-optic disks to provide needed storage capacity. Frequently, these disk drives are used in combination to provide increased reliability though inter-disk coding techniques and through disk sparing. The disk drives are often packaged into arrays in order to decrease the amount of physical space needed to house them and in order to physically associate disks that are used combinations and as spares.
Regardless of the drive packaging arrangement, three problems have to be addressed: how to cool the drives, how to shield the drives to prevent the emission of excessive electromagnetic radiation and how to secure the drives in such a way as to minimize rotational vibration. Prior-art solutions to these problems typically entail housing each disk drive in its own metal, or combination metal and plastic, structure that allows air to flow around the drives and provides a conductive enclosure for emission control purposes. This conductive enclosure is then electrically connected to a common chassis ground using spring fingers or metal gaskets. However, the housing structure effectively increases the width of each disk drive and limits the density with which the drives can be packaged. For example, it is very difficult to fit more than thirteen conventional drives having a 3.5-inch, low-profile form factor into an Electronic Industry Alliance (EIA) standard 19-inch rack-mountable chassis using this technique.
Consequently, there is a need for packaging method and apparatus that enables a larger number of disk drives to be housed in the width available in a standard 19-inch rack than is possible with prior art methods and apparatus while still providing adequate cooling, radiation shielding and a mechanically secure method of mounting.
In accordance with the principles of the invention, disk drive packaging apparatus has a chassis with open ends that encloses all of the disk drives. The open ends of the chassis are covered with conductive screens. A disk-drive carrier is provided for each drive that holds, but does not enclose, the disk drive. The screens provide both emission containment and guarantees adequate air distribution for cooling. Because the screens are able to contain the radiation emission, conductive enclosures are not needed for each separate drive, with the result that the drives can be packed more densely.
In one embodiment, at least one conductive screen is mounted in a bezel assembly that is removably attached to one of the open chassis ends.
In another embodiment at least one, and preferably two fans are located in the chassis to draw air across the disk drives. The conductive screens insure uniform air distribution across all disk drives.
In still another embodiment, the disk drive carrier is fabricated entirely of a non-metallic material, such as a polymeric material, including carbon-reinforced nylon and glass-reinforced polycarbonate materials.
In yet another embodiment, the conductive screens have an open area that is approximately 52% of the total screen area that contains excess emissions.